Solving RF Complexity in the Connected Car

The complexity of wireless communications in vehicles is increasing at an extraordinary pace, and the impending arrival of 5G will pave the way for even greater reliance on RF technologies. Today, vehicles may rely on wireless communications for a dozen or more functions, ranging from safety features and navigation to infotainment and keyless entry (Figure 1). Over the next few years, those functions will increasingly expand to include autonomous driving, as well as communications with infrastructure and the Internet of Things – especially as the connected world transitions from 4G to 5G.

Figure 1. Automotive system technologies

The growing RF complexity already creates significant challenges for automotive manufacturers, and the challenges will increase as cars rely more heavily on wireless communications. To help make the leap to 5G, the industry established the 5G Automotive Association (5GAA) in 2016 to support and guide the 4G and 5G standardization, develop testing, promote solutions, and accelerate commercial availability of automotive products. In the meantime, the challenges facing automotive manufacturers include evolving their designs to support much faster cellular data rates by migrating from the CAT4 modem standard (150 Mbps download speed) to CAT16 (1 Gbps) and beyond.

Communications Complexity Drives Search for Proven Solutions

The RF complexity and rapid pace of change are challenging automotive manufacturers’ ability to quickly develop, test, implement and deliver products to consumers. Designs must integrate highly complex wireless systems while ensuring the guaranteed quality of service, reliability and robustness that the automotive industry expects. Furthermore, these standards must be achieved in the production design because it is usually unacceptable or even impossible to redesign products after they have been released to consumers.

To meet these challenges, automotive manufacturers need proven wireless components and modules that they can integrate into vehicles. To obtain them, they are increasingly turning to suppliers with extensive experience in the wireless networking and mobile communications industries, which have been delivering products to smartphone manufacturers and mobile network operators for many years. This background also provides valuable expertise and guidance that can help automotive manufacturers understand and overcome potential obstacles related to standards compliance, regional requirements and antenna technology. Such expertise becomes particularly important as vehicles integrate a growing range of wireless protocols and frequency bands. This can help to solve complex 4G and 5G challenges, such as multiple input-multiple output (MIMO) and carrier aggregation (CA) – two widely used techniques for delivering higher data rates.

Critical Factors for Automotive Communication Design

As wireless communications become responsible for more of the car’s functions, several design factors are critical to achieving success in automotive designs.

Ruggedness and reliability. Wireless components must withstand rigorous everyday use in extreme temperatures and humidity, as well as surviving physical abuse. To ensure that products continue operating reliably in these conditions, RF components designed for automotive use must be qualified to specific automotive industry standards.

IATF 16949 is the global automotive industry standard for quality management systems; the industry generally expects parts to be manufactured, assembled and tested in IATF 16949-qualified facilities. In addition, each component must survive a battery of industry-standard tests during the pre-release qualification phase:

AEC-Q100 defines the standard tests for active components, such as switches and power amplifiers (PAs).

AEC-Q200 covers similar tests for passive devices, such as RF filters used in Wi-Fi and cellular communications.

Longevity. Smartphones are generally only used for three to five years. However, cars often remain on the road for a much longer time — 10 years or even more. Therefore, RF components must be highly reliable and available as replacement parts for an extended period.

Coexistence and interference. With so many radios inside today’s autos, engineers must always be aware of the potential for RF interference issues and take a prudent approach to avoiding them. A variety of coexistence filters are available from RF suppliers to address these interference problems and comply with government regulations.

Regional wireless standards. Smartphone makers and automotive manufacturers alike must comply with regional cellular standards and RF spectrum allocations. To keep costs down, smartphone suppliers and automotive manufacturers both try to create as few different models (stock keeping units, or SKUs) as possible. Typically, this means four SKUs respectively covering North America, China, EU and the rest of the world.

DSDA (Dual Sim Dual Active) radios. DSDA technology uses two separate transceivers and antenna pathways to support two different cellular networks simultaneously (Figure 2). This enables auto manufacturers to provide specific contracted services while offering vehicle owners the ability to add their preferred carrier. Although DSDA is not currently widely used, as markets mature more use cases will emerge making this technology more wide-spread.

Figure 2. How DSDA technology works

Solving RF Complexity

From a development perspective, it is challenging to deal with the current increases in wireless connectivity while anticipating what 5G will soon bring. Even when using 4G and 5G wireless technology that has been verified in mobile devices, extensive testing is imperative to guarantee reliability and performance in automotive use, due to the additional RF complexity and operating requirements. When designing complex subsystems such as telematics control units (TCUs) and antenna clusters, it is important to keep the following principles top-of-mind.

Integration reduces RF complexity. Integration is always a good way to reduce complexity. The more that designs use highly integrated RF front ends (RFFEs), the better chance of reducing overall design complexity. These devices combine components such as power amplifiers (PAs), switches, low noise amplifiers (LNAs) and filters into a single pre-qualified module. This accelerates design and overall time to market by reducing PCB complexity and the need for external tuning. These integrated RFFEs further reduce complexity by including support for CA, advanced filtering and diversity RF chains. CA, which is being widely deployed by operators worldwide, aggregates spectrum from multiple bands to deliver higher data rates and improve network performance. The CA landscape is extremely complex, with greater than 300 different band combinations used by different network operators. Today’s mobile device RFFEs help to solve CA problems by addressing many of these combinations, and they can help to solve the same challenges in vehicle communication systems.

RF modules and components with proven performance. Many wireless device manufacturers already have large portfolios of proven technology already used in wireless mobile devices. These mobile devices provide reliable and fast access to global wireless networks. Using these proven components can help to guarantee high reliability and performance in automotive wireless systems.

Coexistence and interference filters. Coexistence filters help reduce interference issues, which can cause receiver sensitivity problems and regulatory non-compliance. When using highly integrated RF modules, multiple radio transceivers operate in close proximity to each other. It is possible for the transmit power of one RF chain to exceed the power level of the signal reaching a nearby receiver, which can cause receiver sensitivity issues. Many integrated RFFEs therefore include embedded filters to reduce the possibility of interference, particularly between adjacent bands. For example, coexistence filters are used in mobile devices and automotive Wi-Fi systems to enable Wi-Fi to operate concurrently with cellular Band 41.

Summary

By 2025, every new vehicle on the road will be wirelessly connected in some way. Automotive manufacturers will rely on wireless communications for an extremely wide range of functions, including vehicle safety and control. Those functions will require support for many cellular technologies – including 2G, 3G, 4G and 5G, as well as Wi-Fi, Bluetooth and near-field communications (NFC). As the automotive RF environment becomes more complex and challenging, it will become increasingly important to use technology that has already been proven to communicate reliably in the similarly complex world of mobile devices.

Authors

Berry Leonard – Product Line Director – Automotive

Connie MacKenzie – Senior Product Marketing Manager

David Watson – Senior Marketing Manager

David Schnaufer – Technical Marketing Manager

About Qorvo

Qorvo (NASDAQ:QRVO) makes a better world possible by providing innovative RF solutions at the center of connectivity. We combine product and technology leadership, systems-level expertise and global manufacturing scale to quickly solve our customers' most complex technical challenges. Qorvo serves diverse high-growth segments of large global markets, including advanced wireless devices, wired and wireless networks and defense radar and communications. We also leverage our unique competitive strengths to advance 5G networks, cloud computing, the Internet of Things, and other emerging applications that expand the global framework interconnecting people, places and things. Visit www.qorvo.com to learn how we connect the world.

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